Metamorphosis

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Metamorphosis is a biological process whereby a creature rapidly changes from one physical form to another within the course of its lifetime. There are two types of metamorphosis in which an insect can go through. They are known as incomplete and complete. The most popular insect that goes through complete metamorphosis is known as the monarch butterfly. The monarch butterfly goes through different stage in order that it can survive in different environments. There are three stages in both of types of metamorphosis. The incomplete stages are the egg, nymph and adult stages. The complete stages are the larvae, pupa and adult stages. Although it may seem as though they are the same they are both very different.(Purves, 648)

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Complete

Moth metamorphic stages

Complete metamorphosis is a process in which an animal's appearance changes completely. It often changes so much that the different stages seem as though they were different animals. One of the most prominent animals that goes through this process is known as the Lepidopteran (butterflies and moths). The insects that undergo this process go through a series of three stages. These stages are the larva stage, then the pupa stage (chrysalis or cocoon), followed by the adult stage. Complete metamorphosis is also known as holometabolism.[1]

The process of complete metamorphosis destroys most of what was left of the larvae, and the organisms is completely reformed into the adult. The insect uses some of the nutrients that were left from the larvae to help form the adult. Some of the specific species that go through complete metamorphosis are the horse fly, monarch butterfly, cockroach, lady bird and the mayfly.[2] The first stage of the monarch is that the insects lays an egg. From that point the egg will then hatch and out comes a caterpillar. Once the caterpillar has grown to its capacity it will attach to a branch and form a hard shell around its body. This is known as a chrysalis. After a while the chrysalis will then split and an adult will emerge from the shell. [3]

Incomplete

Another type of metamorphosis is known as incomplete metamorphosis, which is also referred to as hemimetabolism. This phase is unlike the complete metamorphosis because it goes through three stages, but they are different then the complete stages. The stages of the incomplete metamorphosis are egg, nymph and adult. These stages are not equivalent to the complete stages in that the nymph is not the same as the pupa. The nymph is like a miniature version of the adult in that they have the same features. The stages of the incomplete metamorphosis are gradual and are not drastic. Some examples of this would be earwigs, dragonflies, crickets, and praying mantis. The insects of the incomplete nature are also further split up into two other groups known as paurometaboly and heterometaboly. In the paurometaboly an insect will live in the same environment when it is a nymph and when it is an adult. Two insects that are in this group are the grasshoppers and the true bugs. The heterometaboly are the opposite of this in that they live in different environments when they are a nymph and when they are then an adult.[4]

Amphibian Metamorphosis

Amphibian metamorphosis is when a single amphibian changes from a larvae, otherwise known as a tadpole, to an adult. Usually, eggs are laid in water. The tadpole then emerges from the egg and swims freely within the water. The tadpole has gills, a tail and a small circular mouth. The tadpole will grow, until it begins metamorphosis. Metamorphosis begins with the development of the hind legs, then the front legs. The lungs develop, and the tadpole begins to swim to the surface of the water to breathe. The intestine shortens to accommodate a carnivorous diet, and the eyes migrate rostrally and dorsally. In frogs the tail is absorbed by the body, for the last stage of metamorphosis.

The process of metamorphosis is often varied within groups of amphibians. Some species of salamander do not need to metamorphose to be sexually mature, and will only metamorphose under certain environmental stresses. Many species of frog from the tropics lay their eggs on land, where the tadpoles undergo metamorphosis within the egg. Once they hatch, they are immature copies of the adults, sometimes possessing a tail which is re-absorbed in a couple of days. Situations such as these have allowed for a large diversity in the way amphibians develope and mature.[Reference needed]

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References

Purves, William. Life the Science of Biology. 2005. Couriers Company Inc.